1. Field of the Invention
The present invention relates to a method for manufacturing a liquid discharge head which discharges a desired liquid with the creation of bubbles by the application of thermal energy or the like. More particularly, the invention relates to a method for manufacturing a liquid discharge head that uses movable separation film displaceable by the utilization of the creation of bubbles.
In this respect, the term xe2x80x9crecordingxe2x80x9d referred to in the description of the present invention not only means the provision of meaningful images, such as characters, graphics, on a recording medium, but also, means the provision of meaningless images, such as patterns on it.
2. Related Background Art
There has been known conventionally the ink jet recording method, that is, the so-called bubble jet recording method, in which by the application of thermal energy or the like to ink, the abrupt change of its states is generated with the resultant voluminal changes in ink (the creation of bubbles), and then, ink is discharged from the discharge ports by the acting force based upon this change of states, thus enabling ink to adhere to a recording medium for the image formation. As disclosed in Japanese Patent Publication Nos. 61-59911 and 61-59914, in general, the recording apparatus using this bubble jet recording method comprises discharge ports that discharge ink; ink flow paths communicated with the discharge ports; and heat generating members (electrothermal converting means) arranged in the ink flow paths, respectively, to function as means for generating energy used for discharging ink.
By use of the recording method described above, it is possible to record high quality images at high speeds with a lesser amount of noises. At the same time, this method enables the discharge ports to be arranged in high density for discharging ink, thus making it possible to record images in high resolution with a smaller apparatus. Moreover, there are many advantages, such as to make it easier to obtain color images. As a result, the bubble jet recording method has been utilized widely in recent years for the office equipment, such as a printer, a copying machine, a facsimile apparatus. This method has also been utilized for the industrial system, such as textile printing apparatus.
On the other hand, for the-conventional bubble jet recording method, there is encountered the problem of the burnt ink accumulation on the surface of the heat generating members in some case, because the heat generating members are repeatedly heated while in the state of being in contact with ink. Also, if the liquid that should be discharged tends to be easily deteriorated by the application of heat or if the liquid is the one for which the bubbling capability cannot be obtained sufficiently, it becomes difficult to perform discharges in good condition in some cases by the adoption of the direct heating method for creating bubbles by use of the heat generating members described earlier.
Under the circumstances, the applicant hereof has proposed a method whereby to discharge the discharging liquid by foaming the bubbling liquid by the application of thermal energy through flexible films each arranged to separate the bubbling and discharging liquids as disclosed in the specification of Japanese Patent Application Laid-Open No. 55-81172. For this method, the structure of the flexible films and the bubbling liquid is arranged so that each of the flexible films is installed on the part of each nozzle. Further, in the specification of Japanese Patent Application Laid-Open No. 59-26270, there has been disclosed the structure in which a large film is used to separate the entire head body into the upper and lower portions. This large film is pinched by two plate members that form the liquid paths. This film is provided for the purpose of preventing liquids in the two liquid paths from being mixed with each other.
Meanwhile, in the specification of Japanese Patent Application Laid-Open No. 05-229122, there has been disclosed the method in which the bubbling liquid itself is characterized and its bubbling property is made to present a lower boiling point than the discharging liquid to be used or in the specification of Japanese Patent Application Laid-Open No. 04-329148, there has been disclosed the one whereby to use the liquid having conductivity as the bubbling liquid.
However, the liquid discharge method that uses the conventional separation films as described above is just structured to separate the bubbling liquid and the discharging liquid or just to improve the property of the bubbling liquid itself. Thus, non of them have reached the practical standard as yet.
The inventors hereof have ardently studied on the liquid droplet discharge that uses the separation films centering on the phenomena of the discharge liquid droplets, and have reached the conclusion that the efficiency of the liquid discharges with the bubble formation by the application of thermal energy tends to be lowered when the discharges are effectuated through the intervention of the changing separation films, and that this inefficiency impedes the method from being used practically as yet.
Therefore, the inventors hereof have further studied on the provision of the liquid discharge method and apparatus with which they can attain the higher standard of liquid discharges, while keeping the effect of the intended function of the separation film as it is.
During such studies, the inventors hereof have designed the present invention that provides an epoch-making liquid discharge head capable of enhancing the discharge efficiency of the liquid droplet discharges, as well as capable of stabilizing and increasing the volume of the discharge liquid droplets or discharge speeds. The invention also provides the method of manufacture therefor.
It is a first object of the invention to provide a method for manufacturing liquid discharge heads with a simpler method in good precision, which is capable of manufacturing a liquid discharge head structured to be able to substantially separate the discharging liquid and the bubbling liquid by use of the movable film, or more preferably, structured to be able to separate them completely by use of thereof.
It is a second object of the invention to provide a method for manufacturing a liquid discharge head capable of obtaining higher discharge power without spoiling the discharge efficiency with the structure described above, which is not only capable of preventing the pressure from escaping to the upstream side, but also, capable of guiding the pressure in the direction of the discharge ports.
Also, it is a third object of the invention to provide a method for manufacturing a liquid discharge head capable of reducing the amount of the substance accumulated on the heat generating elements (members) due to the structure formed as described above, at the same time being able to discharge liquid with a good efficiency, but not to exert the thermal influence on the liquid to be discharged.
Also, it is a fourth object of the invention to provide a method for manufacturing a liquid discharge head having a wider freedom of liquid selections irrespective of the viscosity or the material composition of the liquid to be discharged.
In order to achieve the objects described above, the method of the present invention for manufacturing a liquid discharge head, which is provided with a discharge port for discharging a liquid droplet; a first liquid flow path for supplying discharging liquid to the discharge port; a second liquid flow path for bubbling liquid supplied thereto; a heat generating element for the formation of a bubble creation region arranged for the second liquid flow path; a movable film supporting member for supporting the movable film separating the first liquid flow path and the bubble creation region completely, and being displaceable by the bubble created on the heat generating elements; and discharging a liquid droplet from the discharge port by the utilization of thermal energy provided by the heat generating elements, comprises the steps of forming the movable film supporting member; forming on the surface of the substrate becoming the movable film supporting member the recessed portion corresponding to the movable region of the movable film; providing a material becoming the movable film on the entire surface of the substrate having the recessed portion provided therefor; removing the portion including the movable region on the substrate from the reverse side of the substrate having the movable film provided therefor; and forming the slacked configuration on the portion of the movable region of the movable film.
In accordance with the invention described above, the recessed portions are formed on the portions on the surface of the substrate that become each of the movable regions of the movable film when the movable film supporting member is formed. Then, with the formation of the movable film on the entire surface of the substrate where the recessed portions are formed, it is easier to form the movable film having its slacked movable regions, that is, each region which is not supported by the movable film supporting member. In this way, with the formation of each movable region in the slacked configuration toward the liquid discharge head substrate, it becomes easier for the movable film to be displaced and transfer the bubbling energy efficiently. Particularly, with the performance of the isotropic etching for the formation of the recessed portions, the section of each of the recessed portions becomes substantially circular to make it possible to form the movable film to be easily displaceable. Also, it becomes possible to arrange the slacked portions of the movable film in the liquid flow paths in good precision.
Then, for the liquid discharge head structured in accordance with the present invention described above, the first liquid flow paths communicated with the discharge ports to supply the discharging liquid, and the second liquid flow paths to which the bubbling liquid is supplied are separated completely by the separation film. In the second liquid flow paths, the bubble creation regions are contained. Then, the movable film is displaced to the first liquid flow path side along with the development of each bubble in the bubble creation regions. With the pressure thus exerted, liquid is discharged for each of the discharge ports. Here, each movable region of the movable film, which is not supported by the movable film supporting member, is formed in the slacked configuration toward the liquid discharge head substrate. As a result, the displacement of the movable film becomes easier to transfer the bubbling energy efficiently.
In this respect, the term xe2x80x9cupstreamxe2x80x9d and the term xe2x80x9cdownstreamxe2x80x9d are used as expression to indicate the direction of liquid flowing toward the discharge ports from the supply source of the liquid through the movable regions of the movable film or to indicate the direction in which this structure is formed.